The present invention concerns a method of manufacture of tires and a radially expansible assembly drum making it possible to use the method.
The invention concerns, in particular, the manufacture of a tire including a carcass reinforcement and at least one reinforcing bead wire in each of the beads of the tire, inside which the carcass reinforcement forms a turn-up and the two beads of which have different diameters.
The building of this type of tire requires the use of an assembly drum that itself presents sites for receiving beads of different diameters. However, this requirement for accommodating different diameters presents production problems and difficulties in controlling the quality and reliability of the tires produced.
It is important, for the quality and reliability of the tire, to place the components of the carcass reinforcement, such as plies, etc., on the drum evenly in terms of geometry, and therefore centering and imparting tension in the products. This seems particularly difficult on a drum in which the diameters of the bead receiving sites are different. However, it is possible to overcome these difficulties by placing the different products slowly and carefully by hand. It is clear that this solution is not adaptable to the industrial context.
Furthermore, construction of the turn-up of the carcass reinforcement in the beads of the tire necessitates stretching of the carcass reinforcement at the points around which the carcass reinforcement rotates, which is difficult to accomplish simultaneously at two sites of different diameters.
The invention is directed to overcoming these problems.